© Masson, Paris, 1983. Ann. Parasitol. Hum. Comp., 1983, t. 58, n° 6, pp. 539-547. LEISHMANIASIS IN TUSCANY (ITALY) : VI I I — Human population response to leishmanin in the focus of Monte Argentario (Grosseto) and epidemiological evaluation S. BETTINI*, M. GRAMICCIA**, L. GRADONI**, E. POZIO**, S. MUGNAI*** and M. MAROLI** SUMMARY. A skin test survey carried out in the towns of Porto St. Stefano and Porto Ercole showed a total positivity rate of 15.3 %. The progressive increase of positivity according to age was not uniform but similar for the two towns since the values concerning the last two age groups did not follow the general trend of the graph but were lower than expected. The possible causes of this phenomenon have been discussed. The absence of overt visceral leishmaniasis cases in recent years and the concomitant high prevalence of canine leishmaniasis have been considered in the light of the occurence of infectious diseases and the increase of the nutritional levels in the local human population. Leishmaniose en Toscane (Italie) ; VIII — Réponse à la leishmanine par la population humaine du foyer de Monte Argentario (Grosseto) et évaluation épidémiologique. RÉSUME. Une enquête par intradermoréaction à la leishmanine réalisée dans les deux petites villes de P. St. Stefano et P. Ercole a montré un taux de positivité de 15,3 %. La hausse de posi­ tivité en fonction de l ’âge n’était pas uniforme mais similaire pour les deux villages puisque les valeurs concernantes les tranches d’âges les plus hautes n’ont pas suivi la courbe mais étaient plus basses que attendues. Les causes possibles de ce phénomène ont été discutées. L ’absence dans les années récentes de cas cliniques de leishmaniose viscérale et la concomitante prévalence élevée de leishmaniose canine ont été considérés à la lueur de la présence de maladies infectieuses et de la hausse des niveaux nutritifs parmi la population humaine locale. Introduction Human visceral leishmaniasis has been declining remarkably during recent years in Italy. On the other hand, canine leishmaniasis is generally still present at high levels in former VL foci. This is the case of the focus of Monte Argentario, a coastal Commune of the province of Grosseto, Tuscany, where work on sandflies (Maroli * Cattedra di Parassitologia (Prof. S. Bettini), Facoltà di Scienze, Università di Cagliari, 09100 Cagliari, Italia. ** Laboratorio di Parassitologia, Istituto Superiore di Sanità, viale Regina Elena 299, 00161 Roma, Italia. *** County Doctor of Porto Ercole, Monte Argentario, Grosseto, Italia. Accepté le 26 Mai 1983. Article available at http://www.parasite-journal.org or https://doi.org/10.1051/parasite/1983586539 540 S. BETTINI et al. and Bettini, 1977), on canine leishmaniasis (Gradoni et al., 1980 ; Pozio et al., 1981a) and on wild Leishmania reservoirs (Pozio et al., 1981b), had been previously carried out. In the present note are given the results of a leishmanin skin test (LST) survey on the human population of this area, performed during July-August 1981. Area involved M. Argentario is a fossil island, geologically distinct from the inland territories of the province of Grosseto, thus its flora and fauna are peculiar of this area (Pozio et al., 1981a). Its surface is of about 61 km2 and its maximum height 635 m. The majority of the human population lives in the two towns of Porto Santo Stefano, with about 8,000 inhabitants, and Porto Ercole, with about 3,000 ; the remaining 3,000 inhabitants live scattered in farm houses, mainly along the coast. This area is one of the most populated of the province of Grosseto, according to the 1971 census. The total number of inhabitants has not changed considerably during the last 35 years (10,039 in 1936, 10,692 in 1951, 11,569 in 1961 and 13,676 in 1971) (Istat, 1977). Human VL cases In the last 40 years, 16 VL clinical cases have been reported from this territory ; 15 of them during the post-war period (Seganti and Palombelli, 1955) and one in 1973 (Bettini et al., 1977). All cases lived in the town of P. St. Stefano and its sorround- ings. During pre-war time, the limited knowledge of this disease and high frequency of malaria cases in the Grosseto province might have influenced the number of VL cases reported. Canine leishmaniasis A survey on canine leishmaniasis (Gradoni et al., 1980 ; Pozio et al., 1981a) has been carried out in this territory over a two year period (1979-80) ; 171 dogs (out of a population of about 250) have been examined, 23,9 % were positive in the immuno­ fluorescence antibody test (IFAT) and 59 % of them displayed no signs of the disease. The infected dogs were distributed over the whole territory, inside and around the two towns, as well as in the scattered farms. The highest frequency of IFAT positive subjects (69.3 %) was observed in the south-western area. A few feral dogs were found, thriving close to garbage dumps, others living in packs in the “ bush” . The canine population increases considerably during summer, in connection with the high number of tourists. Seven Leishmania isolates from dogs of M. Argentario have shown, on enzyme typing, to be identical to typical L. infantum (Gramiccia et al., 1982). LEISHMANIASIS IN TUSCANY (ITALY) 541 Wild reservoirs Wild mammals, in particular the red fox, Vulpes vulpes, are abundant in the area. In one locality, in the surroundings of P. Ercole, the black rat, Rattus rattus, has been found infected (Pozio et al., 1981b), the enzyme typing of the isolate showing it to be identical to typical L. infantum (Gramiccia et al., 1982). In Tuscany, R. rattus has been proved experimentally to play the role of wild reservoir of VL (Gradoni et al., 1983). Search for Leishmania has not been carried out in any other wild mammal species of M. Argentario. In two other areas, one at about 40 km (Baccinello, Grosseto) and the other at 5 km from M. Argentario (Orbetello Scalo), a fox and two dogs have been found infect­ ed with a variant of L. infantum (Bettini et al., 1980 ; Gramiccia et al., 1982). Vectors Phlebotomus perniciosus, the predominant species, is highly suspected of being the local vector of VL (Corradetti and Neri, 1955 ; Maroli and Bettini, 1977 ; Biocca et al., 1977). Only a few samples of P. perfiliewi have been caught in the area (Maroli, personal communication). Specimens of P. perniciosus, trapped in a farm near P. Ercole and fed on a naturally infected dog and on R. rattus experimentally infected with L. infantum, have become infected at a frequency rate of 53 % and 21-25 % respectively (Maroli et al., 1980 ; Gradoni et al., 1983). P. perniciosus has been readily caught on human bait (Maroli et al., in press). Its attraction to R. rattus in nature has been demonstrated (Gradoni et al., 1983). Materials and methods The leishmanin used in the present survey was obtained from Dr. D. A. Evans of the Department of Protozoology, London School of Hygiene and Tropical Medicine. It was prepared from a dog isolate, originating from the province of Grosseto (Gra­ doni et al., 1980), which, later, on enzyme typing showed to be a variant of L. infan­ tum (Gramiccia et al., 1982). This antigen, used as control on six volunteers that had recovered from overt VL infections, gave an intense skin reaction. The strength of the leishmanin was of 107 organisms/ml. The leishmanin specificity for leishmaniases was demonstrated by several authors, as reported by Pampiglione et al. (1975). The skin test procedure and the reading of the reaction, were carried out according to the method described by Manson-Bahr (1961) and Pampiglione et al. (1975). To avoid “observer variation” , reading of skin reaction was carried out by only one of us (S.B.). Authorization for performing LST on the population of M. Argentario was ob­ tained from the Local Health Unit (USL No. 29) and from Regional authorities. A 542 S. BETTINI et al. poster explaining the purpose of the survey and the principles of skin testing was distributed to schools, out-patients’ clinics and public buildings. The local county doctors and other physicians were informed in detail of the survey’s aim and proce­ dures. The planning of the operations in the elementary, primary and secondary schools was done by the two local school inspectors. Testing on youngsters was performed in school buildings, that on adults and infants in the office of one of the authors (S.M.) at P. Ercole and in the “ Poliambulatorio ” of P. St. Stefano. The survey involved population samples of all ages living either inside the two towns or in the surroundings. A total of 1,818 people, 750 from P. Ercole and 1,068 from P. St. Stefano, have been examined. In the periphery of the two towns, there is no clear cut boundary between urban and rural dwellings, the formers being often surrounded by gardens. In the rural section, fowls and rabbits are often the only farm animals present, but sporadic farms with horses, pigs or cattle may also be found. Every effort has been made to avoid systematic errors in the planning of the survey. Neverthless, the consistency of the age groups above 55 years in P. St. Stefano could not be avoided to be inferior to that of the other age groups. In P. Ercole, on the other hand, all age groups were homogeneous. The nonresponse of P. St. Stefano’s target group segment could not be overcome even by carrying out a second skin survey preceded by an intense propaganda. It appears therefore that our inquiry had raised little interest in the majority of adults of P.